A B737-300 ACFT DSNDING INTO ZZZ HAS AN UNCOMMANDED ROLL OF 15-20 DEGS.

Narrative

DURING DSCNT ON BACK COURSE LOC; ACFT ROLLED R; YAW DAMPER INDICATOR SHOWS FULL L DEFLECTION. ACFT WAS BROUGHT BACK ON LOC AND NO FURTHER PROBS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: AS THE B737-300 DSNDED ON THE LOC; IT MADE AN ABRUPT ROLL TO THE R OF 15-20 DEGS. AUTOPLT WAS OFF AND THE YAW DAMPER INDICATOR SHOWED FULL L DEFLECTION. ACFT WAS EASILY ROLLED BACK TO LEVEL WITH AILERON AND RUDDER INPUTS. BECAUSE THE CAPT WAS UNSURE OF THE CAUSE OF THE ROLL; HE WROTE THE EVENT UP IN THE LOGBOOK WHICH GNDED THE ACFT. ACFT WAS INSPECTED AND SEVERAL INTERVIEWS FOLLOWED THE EVENT WITH HIGH LEVEL COMPANY OFFICIALS. ONE UNION SAFETY OFFICIAL BELIEVES IT WAS SOME LEFTOVER WAKE TURB THAT WAS ENCOUNTERED. THE CAPT DOUBTS THAT WAS THE CASE; HE IS JUST UNCERTAIN; WHICH IS WHY HE WROTE UP THE UNCOMMANDED ROLL INTO THE LOGBOOK. ACFT WAS THOROUGHLY INSPECTED AND FLC INTERVIEWED SEVERAL TIMES TO MAKE CERTAIN THE APPROPRIATE ACTION WOULD TAKE PLACE. ACFT HAS BEEN RETURNED TO SVC. SUPPLEMENTAL INFO FROM ACN 376160: ACFT ROLLED R (UNCOMMANDED).